ENDOSCOPIC SURGERY OF THE POTENTIAL doc

Amanti Assistant Professor of Surgery, Department of Surgery, University of Rome “La Sapienza”, Rome, Italy A.. Farinon Professor of Surgery, Department of Surgery, University of Rome “T

ENDOSCOPIC SURGERY OF THE POTENTIAL ANATOMICAL SPACES

Endoscopic Surgery of the Potential Anatomical Spaces

Edited by

ATTILIO MARIA FARINON,MD, FACS

Professor of Surgery and Chairman,

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“And it ought to be remebered that there isnothing more difficult to take in hand, moreperilous to conduct, or more uncertain in itssuccess, than to take the lead in the introduc-tion of a new order of things Because the in-novator has for enemies all those who havedone well under the old conditions, andlukewarm defenders in those who may dowell under the new.”

N Machiavelli: The Prince (Chapter VI), 1531

Radiology of the anatomical compartments

Ettore Squillaci, Rita Cammarata, Giovanni Simonetti

Video-assisted thoracoscopic access to the mediastinum

Tommaso Claudio Mineo, Eugenio Pompeo

Minimally invasive access to the axilla

Gianfranco Tucci, Claudio Amanti

Video-assisted approach to the retroperitoneum

Francesco Micali, Flavio Forte

Extraperitoneal video-assisted approach to the abdominal aorta

John J Castronuovo

Chapter 9 109Total extraperitoneal approach (TEP) for inguinal hernia repair

Francesco Mosca, Andrea Pietrabissa, Carlo Moretto

Video-assisted access to the subfascial space of the leg

Francesco Rulli, Gabriele Galatà, Michele Grande

New Technologies in minimally invasive surgery

Angelo Benevento, Luigi Boni

viii

List of contributors

C Amanti

Assistant Professor of Surgery, Department of Surgery, University of Rome

“La Sapienza”, Rome, Italy

A M Farinon

Professor of Surgery, Department of Surgery, University of Rome “Tor Vergata”, Rome, Italy

F Forte

Clinical Researcher in Urology, Department of Surgery, University of Rome

“Tor Vergata”, Rome, Italy

G Galatà

Resident in General Surgery, Department of Surgery, University of Rome “Tor Vergata”, Rome, Italy

M Grande

Assistant Professor of Surgery, Department of Surgery, University of Rome

“Tor Vergata”, Rome, Italy

G Materazzi

Clinical Researcher in Surgery, University of Pisa, Pisa, Italy

Professor of Thoracic Surgery, Department of Surgery, University of Rome

“Tor Vergata”, Rome, Italy

Associate Professor of Surgery, Department of Surgery, University of Rome

“Tor Vergata”, Rome, Italy

G Simonetti

Professor of Radiology, Institute of Radiology, University of Rome “Tor Vergata”, Rome, Italy

E Squillaci

Associate Professor of Radiology, Institute of Radiology, University of Rome

“Tor Vergata”, Rome, Italy

G Tucci

Associate Professor of Surgery, Department of Surgery, University of Rome

“Tor Vergata”, Rome, Italy

x

“Anatomical potential spaces” is an attractive and no more abstract conceptthat offers new perspectives to a surgical world that is rapidily changing andbecoming more complex

Powerful new technologies demand our attention and testify that our clinicalwork and research are deeply influenced by surgical innovations These latterdramatically modified approaches to treatment through the introduction of en-tirely new interventions such as minimally invasive surgical procedures, whosereal appeal is represented by less invasiveness

This constantly evolving research environment has gained large acceptance bysurgeons accustomed to prompt adaptation to a new trend and inclined to nim-ble behaviour in the face of innovations This behaviour, however, requires arigorous control in order to lead to more reliable, evidence-based practice and

to slow or halt the enthusiasm for some harmful or unhelpful treatments, cially if they are proven to be no better than standard procedures

espe-This particular area of concern has received our attention: to understandwhether innovations should be considered as evolutionary variations on astandard procedure or the first stage of what should become recognized as aformal surgical research project

ATTILIO MARIA FARINONA

Professor of General Surgery University of Rome “Tor Vergata”

For they inquire of the parts…but they inquire not of the secrecies of the passages.

Francis Bacon, The Advancement of Learning, 1605

Francis Bacon found many deficiencies in medical science and in particular

in ‘the inquiry which is made by anatomy’ Four hundred years later, there areareas still inadequately recognised by standard topographical and surgical anat-omy, though most of these areas have in the past attracted transient and subse-quently forgotten interest One such area is a true passage of secrecy: the anat-omy of the potential anatomical spaces

THE SEMANTICS OF SPACES

Despite the conventions of common usage, space is no longer simply athree-dimensional, topographical concept For Kant (Kemp Smith, 1933) space

was not a concept at all, but a pure a priori intuition, something which had to be

accepted for the rest of his system to work The addition of the indefinite article– from ‘space’ to ‘a space’- may change the concept completely One wondershow such a change may be expressed in languages which lack such an article:context must suffice Today, the meaning of ‘space’ depends upon the realm inwhich it is used Architectural space is functional: its control, delimitation andenvisaged usage determines the shape of structures built to enclose or reveal it(Lym, 1980) Postmodern space encompasses the geographical (Diprose and

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A.M Farinon (ed.), Endoscopic Surgery of the Potential Anatomical Spaces, 1–8.

© 2005 Springer Printed in the Netherlands.

Ferrell, 1991), the cultural (Perec, 1997) and the social Non-Euclidean matical space (Sutherland 1975) is a virtual, multi-eponymous and multidi-mensional wonderland within which special properties appear Electronic vir-tual space (Shields 1996) has its own vocabulary: cyberspace and hyperspacehave emerged What does a space mean in the realm of surgical anatomy?

Anatomists have had difficulty with the definition and concept of cal space It may be that alternative words will be found more accurate in ex-pressing the anatomical entity ‘Cavity’ has its own accepted meaning; ‘inter-val’ has been suggested (Stockwell 1999) ‘Compartment’ may be moreaccurate (Newell 1999)

anatomi-What then is an anatomical space? anatomi-What do you see and understand whenyou hear the phrases ‘deep perineal space’, ‘palmar space’, ‘submandibularspace’? Is the ‘space’ here the same sort as the epidural or the subphrenic? Doyou see such a space as an actual three-dimensional gap? If an anatomical space

is not the same as an anatomical cavity (synovial, peritoneal), what defines thedifference? Is it only semantic?

Potential space

This term is commonly used to describe a space which is not evident until it

is created by distension or by blunt dissection Grodinsky and Holyoke (1938)refer to potential fascial spaces without prior definition of the term Haines(1991) defined a “true potential space” as “one that may be created withoutdisrupting the normal structure/functional integrity of the tissues involved inthe creation of the space [and which is] lined by a mesothelium which isnormally covered by small amounts of a serous fluid” Haines also notes that

such spaces “may be repeatedly rr created and obliterated without resulting in sue damage or requiring tissue repair” The potential spaces considered in thisbook would not satisfy these strict criteria

tis-It could however be argued that all ‘anatomical spaces’ are artefactual, and

that ‘potential space’ is both an abstract concept and an oxymoron Is there any

‘space’ there at all before the dissector or the disease allows fluid (gaseous orliquid) to accumulate and thereby to separate tissue planes?

2 Endoscopic surgery of the potential anatomical

Connective tissue planes whose adjacent surfaces are normally connected

by a thin layer of relatively sparse, loose areolar tissue are not strictly ‘potentialspaces’ even though the surfaces may easily be separated Such separation en-tails tissue damage, albeit minimal In Quain’s Anatomy, the buccopharyngealfascia was described as “connected behind to the prevertebral fascia only byvery loose areolar tissue, the meshes of which are readily distended by fluid,

thus giving rise to the so-called retropharyngeal space The loose tissue is tinued without interruption along the oesophagus into the thorax, so that the ar-

con-tificial cavity may be extended downwards into the posterior mediastinum”.

(Thane 1894; author’s emphases)

Normal, traditional ‘spaces’ unlined with mesothelium but having tial contents, like the palmar and perineal ‘spaces’, may be more correctly de-scribed anatomically as compartments, but custom and everyday clinical usageprevail over pedantic accuracy

substan-HISTORICAL USAGE

Spaces in the dead

Having examined the semantics and accepted the pragmatic concept of an

‘anatomical space’, let us look at the history of the usage of the phrase

It has been suggested that anatomical ‘spaces’ were first recognised and fined only in the preserved cadaver, and that the concepts of fascial planes andstructural spaces were developed as a consequence of the definition and con-comitant shrinkage of tissues provided by formalin fixation It has been saidthat “ in many cases the over-enthusiasm with which the new techniqueswere adopted resulted in structures being ‘discovered’ that did not in fact exist”(Dobson, 1956) There may thus have been false extrapolations to the livingsituation

de-The use of formaldehyde as an animal tissue fixative and preservative formicroscopy was first described by Blum (1893), and soon developed in Ger-many for the preservation of dissecting-room cadavers Arthur Keith presentedthe experience of its use at the London Hospital to the May 1896 meeting of theAnatomical Society of Great Britain and Ireland Keith noted that such fixationimproved the cleanliness of the dissection and the definition of fibrous mem-branes (Keith 1896) Tissue shrinkage and the consequent creation ofartefactual ‘spaces’ were not mentioned

In a study of spinal epidural anatomy, Hogan (1991) tried to preclude the ef-fffects of post-fixation shrinkage by examining large cryomicrotome sections ofunembalmed cadavers He found that large areas of the dura were directly incontact with the wall of the vertebral canal, and that the remaining areas were

composed of segmentally compartmentalised fat There was no ‘space’,fluid-filled or otherwise.

Such ‘spaces’ are much less readily visualised in the post-mortem (autopsy)room, where the unembalmed tissues have not shrunk away from each other.Pathologists find cavities and spaces made by disease and injury These may betrue, mesothelial-lined ‘cavities’, opened up by pathological accumulation offluid, or they may be artefactual spaces, pathological cleavage planes (Haines1991) created by haemorrhage or other forms of tissue disruption Fully differ-entiated connective tissue retains the potentiality for cleavage and cavity for-mation (Williams et al., 1985) The occurrence of adventitious bursae andpseudarthroses bears this out The latter forms of ‘cavity’ become lined withtheir own ‘secondary mesothelium’, as do cavities developing around foreignbodies In the absence of such a lining, pathological cleavage planes and otherpathological ‘spaces’ will be obliterated by the healing process

So what were anatomists seeing before the use of formalin fixation becamewidespread? Erasmus Wilson (1857) describes the fasciae of the body in greatdetail While he notes that the aponeurotic (‘deep’) fascia “assists the muscles

in their action, by keeping up a tonic pressure on their surface; aids materially

in the circulation of the fluids in opposition to the laws of gravity”, nowheredoes he refer to the concept of ‘spaces’ limited by the fascial planes which hedescribes Gray (1858) similarly describes fascial topography and attachmentswithout reference to the ‘spaces’ enclosed Richet (1866) describes the fas-cia-bound compartments of the limbs as we understand them today, but uses the

term gaîne which is usually translated into English as ‘sheath’ In a long and

de-tailed treatment of the fasciae of the neck, Richet again describes the

compart-ments which they enclose, but this time uses the term loge The same term is

employed to describe the perineal ‘spaces’

Quain’s Anatomy (Thane 1894) describes the ‘suprasternal space’ betweenthe layers of the deep cervical fascia, but in the leg, though the fasciae are de-scribed in detail, there is no reference to a concept of compartments or ‘spaces’.Treves (1908) describes the intermuscular septa in the leg as ‘forming aT

closed space which might become a definite and well localised cavity for pus’.Grodinsky and Holyoke (1938) suggest that the concept of fascial spaces datesback at least to Juvara (1870)

Spaces in the living

At operation, anatomical ‘spaces’ and ‘planes’ need to be opened up by section before their shape and extent can be demonstrated The dissection may

dis-be blunt, as for ‘true’ cavities or for planes filled with loose areolar connectivetissue It may even consist only of the insertion of a finger or hand: for endo-scopic procedures the ‘body cavities’ are opened up by the prior introduction of

4 Endoscopic surgery of the potential anatomical

gas or saline An active physical process is always required to separate adjacenttissues previously in contact with each other.

Can anatomical ‘spaces’ be demonstrated in the intact living subject bynon-interventional techniques? Again, the problem is the meaning of the word

‘space’ Sargon et al (1996) examined radiological ‘spaces’ in joints, on MRI

of the knee In only one place, half-way through the paper, does the word

‘space’ appear in quote marks The authors acknowledge that they use the term

‘joint space’ to include (as the technique is MRI) both layers of cortical bone, aswell as all non-osseous structures lying between the bone surfaces In generalterms it would seem that the ‘potential’ soft-tissue spaces can only be demon-strated non-interventionally by the relative radiodensity of their boundaries andcontents

SURGICAL ANATOMY OF THE POTENTIAL SPACES Spaces and fasciae: the boundaries of the space and the rele- vant fascial planes

The surgeon must know what defines and limits the particular space Thisincludes the nature and topography of the tissues which form the ‘walls’ of thespace It is also of great importance to know whether surgical access may be re-quired to structures which run in or lie on these walls

In the neck and in the limbs, the spaces are bounded by fascial planes membering that all fasciae are continuous and embryologically precede thecontents of the spaces they limit, it may be useful to think in terms of a ‘fascialskeleton’ In the limbs, the concept perhaps originates with Xavier Bichat, andwas developed by Richet (1866) as a ‘Fibrous System’ Bichat had earlier de-

Re-scribed ‘aponévroses d’enveloppe générale et partielle’ Richet mentions a

collection of prosections by eminent French surgeons and anatomists, madespecifically to demonstrate fascial compartments in the limbs, showing that:

“the whole thickness of the limb between the encircling fascia and the bone isdivided into as many fibrous compartments as there are muscles” Later he re-cognises the fact that “in addition to the fascial coverings particular to eachmuscle, other fascial membranes are found which clearly separate…groups ofmuscles having similar functions, such as the peronei” (author’s translation)

Following Bichat, Richet also uses the term cloison to denote a fibrous

par-tition-wall In the same chapter, Richet gives possibly the earliest description ofcompartment syndrome, and in discussing its management gives the true and

original meaning of débridement.

The concept of a fascial skeleton as a biomechanically functional systemhas been explored much more recently by Gerlach and Lierse (1990) Despitegiving great detail of shape and fibre direction of all lower limb fasciae, the au-thors only mention in passing the fascial ‘cavities’ in which the muscles arecontained.

The potential space and the surgical space

The true shape and size of the potential space must be known or ble It may not be necessary fully to distend the space in order to obtain ade-quate endoscopic access, but information about its dimensions from prior im-aging may be helpful It must also be known before distending and opening thespace whether any anatomical structure is likely to pass through it and cross thefield of view

demonstra-Is the space closed or open?

Richet (1866) described the continuity of the anatomical compartments viadefects or foramina in the walls for the passage of nerves and vessels.Grodinsky and Holyoke (1938) describe multiple communications betweenpotential fascial spaces in the head and neck The surgical implications andpossible use of such pathways have been recognised by Tucci et al (2000) Thesurgeon must know the landmarks which will enable such openings to be local-ised, entered and where necessary enlarged from within the space

SURGICAL ACCESS

Opening or creating the space: techniques and consequences

An active physical process (dissection, distension or disease) is always quired to separate the tissues and open up a potential space, so endoscopic ac-cess will require prior distension or creation of the ‘space’ It will also be neces-sary to develop and refine methods of travelling between spaces via natural orsurgically created pathways (Tucci et al 2000)

re-One of the major concerns relating to the exploration of potential spaces isthe effect of the surgical intervention on the subsequent anatomy and function

of the ‘space’ In the absence of a ‘mesothelial’ lining (Haines 1991), loose andoften sparse areolar tissue lies between fascial planes and may be said origi-nally to ‘occupy’ the potential space This areolar tissue allows movement tooccur between the fascial planes Surgical distension and dissection within the

6 Endoscopic surgery of the potential anatomical

created space must cause an element, however minimal, of tissue damage hesions may then develop and preclude repeated access to the same ‘space’ Itwas part of Haines’ (1991) definition of ‘true’ potential spaces that they “may

Ad-be repeatedly created and obliterated without resulting in tissue damage or

re-quiring tissue repair”

ANATOMICAL SPACES IN THE FUTURE

As we have seen, Bichat and Richet gave us the concept of the fascial ton in the 19th century We are now seeing the recognition of the importance ofthe spaces enclosed, in the widest sense, by that skeleton It is encouraging thatanatomical spaces are now being given due regard in the design of computer-ised anatomical models (Mejino and Rosse 1999)

skele-Historically the development of anatomical knowledge has both pinned and run in parallel with that of the craft and science of surgery Yetagain, as recognised by Fontaine (2000), refinements in surgical techniqueare giving renewed life to a forgotten area of topographical anatomy – theanatomy of the hidden spaces We are at last discovering the secrecies of thepassages

under-Some of the above material has been published in a review article by the author: Anatomical Spaces: a Review Newell RLM Clinical Anatomy 12/1 © 1999 John Wiley and Sons, Inc.

REFERENCES

1. Blum F 1893 Der Formaldehyd als Härtungsmittel Z Wiss Mikr 10:314-315

2. Diprose R, Ferrell R 1991 Cartographies: Post-structuralism and the mapping of bodies

and spaces North Sydney: Allen and Unwin.

3. Dobson J 1956 In Anatomical Techniques D H Tompsett Edinburgh: Livingstone.

4. Fontaine C 2000 Comment from the Editor-in-chief on Tucci et al (2000) Surg Radiol Anat

22:223

5 Gerlach UJ, Lierse W 1990 Functional construction of the superficial and deep fascia

sys-tem of the lower limb in Man Acta Anat 139:11-25

6. Gray H 1858 Anatomy Descriptive and Surgical London: John W Parker and Son

7 Grodinsky M, Holyoke EA 1938 The fasciae and fascial spaces of the head, neck and

adja-cent regions Amer J Anat 63:367-408

8. Haines DE 1991 On the question of a subdural space Anat Rec 230:3-21

9. Hogan QH 1991 Lumbar epidural anatomy Anesthesiology 75:767-775

10 Juvara 1870 quoted in Grodinsky and Holyoke (1938)

11 Keith A 1896 Organs from dissecting-room subjects which had been preserved with

formaldehyd (sic) J Anat Physiol 30:589, xi-xii

12. Kemp Smith N 1933 Immanuel Kant’s Critique of Pure Reason London: Macmillan.

13. Lym GR 1980 A psychology of building Englewood Cliffs: Prentice-Hall

14 Mejino JLV Jr, Rosse C 1999 Conceptualization of anatomical spatial entities in the digital

anatomist foundation model J Am Med Inform Assoc AMIA ’99 Symp Suppl 1999:112-116

15. Newell RLM 1999 Anatomical spaces: a review Clinical Anatomy 12:66-69

16. Oxford English Dictionary 2 nd ed 1989 Oxford: Oxford University Press

17 Perec G 1997 Species of spaces and other pieces J.Sturrock, ed and tr London: Penguin

18. Richet A 1866 Traité Pratique d’Anatomie Médico-chirurgicale 3 rd Ed Paris: Chamerot et

Lauwereyns

19 Sargon MF, Taner D, Altintas K 1996 Examination of joint space by magnetic resonance

imaging in anatomically normal knees Clinical Anatomy 9:386-390

20. Shields R ed 1996 Cultures of internet: Virtual spaces, real histories, living bodies

Lon-don: Sage

21 Stockwell RA 1999 “Macavity’s not there” Reflections on RLM Newell: Anatomical

Spaces Clinical Anatomy 12:70-71

22. Sutherland WA 1975 Introduction to metric and topological spaces Oxford: Clarendon

Press

23. Thane GD 1894 In Schäfer EA Thane GD, eds Quain’s Elements of Anatomy, 10 th Ed Vol.

II II London: Longmans

24. Treves F 1908 Surgical Applied Anatomy 5 th Ed (Keith A rev.) London: Cassell and Co.

Ltd.

25 Tucci GF, Dell’Isola C, Rulli F 2000 The anatomy of “virtual” spaces: the human body as a

matrioska? Surg Radiol Anat 22:223

26. Williams PL, Warwick R, Dyson M, Bannister LH, eds 1985 Gray’s Anatomy 37 th Ed

Ed-inburgh: Churchill Livingstone

27. Wilson E 1857 The Anatomist’s Vademecum London: John Churchill

28. Wilson WJ Erasmus 1838 Practical and Surgical Anatomy London: Longmans

8 Endoscopic surgery of the potential anatomical

CHAPTER 2

RADIOLOGY OF THE ANATOMICAL COMPARTMENTS

Ettore Squillaci, Rita Cammarata, Giovanni Simonetti

Department of Diagnostic Imaging and Interventional Radiology, University of Rome "Tor Vergata", Rome, Italy

PREFACE

The study of the sectional anatomy of the human body goes back to the liest days of systematic topographical anatomy The beautiful drawings of thesagittal sections of the male and female trunk by Leonardo da Vinci(1452-1519), based on some 30 dissections, are examples of the use of bodysections for the study of anatomy These drawings anticipate modern tech-niques by several hundred years [1, 2]

ear-The obstacle to detailed sectional anatomical studies was, of course, theproblem of fixation of tissues during the cutting process

The use of formalin as a preserving fluid was then introduced by Gerota in

1895 and it was soon found to be the method to obtain satisfactory sections offormalin hardened material

The early years of the 20th century saw the publication of a number ofatlases based on this technique

It is always difficult to consider three dimension in the mind’s eye, to beable to view the relationships of the viscera and fascial planes in transverse andvertical section helps to clarify the conventional appearances of the body’sstructure as seen in the operating theatre, in the dissecting room and in textbooks

The introduction of modern imaging techniques, especially Ultrasound,Computed Tomography (CT) and Magnetic Resonance Imaging (MRI), hasenormously expanded the already considerable importance of sectionalanatomy

The radiologist, neurologist, internist, chest physician and oncologist havenow a clear idea of the relationships of the anatomical structures in transverseand vertical section, also helped by 3D imaging

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A.M Farinon (ed.), Endoscopic Surgery of the Potential Anatomical Spaces,9–33.

© 2005 Springer Printed in the Netherlands.

Indeed, precise diagnosis, as well as the detailed planning of therapy and ofinterventional radiology, often depends on a correct cross-sectional approach[3].

COMPUTED TOMOGRAPHY (CT)

The technological advances that have occurred in the biomedical fieldssince the late 1980s have led to the diffusion of CT units with increasingly shortscanning times [1-4]

The advent of spiral CT has represented a true breakthrough in clinical icine

med-This scanning technique, which is based on the continous transition of thepatient and the simultaneous rotation of the tube-detector system, allows theacquisition of body volumes

The advantages of this technique are:

– Optimisation of the X-ray tube: with the same energy load used in spiral

CT, multislice can acquire large volumes of thin slices, or perform withmultiphasic studies on large volumes without interrupting the scans.– Improved temporal resolution: compared with spiral CT, multislice CTcan acquire 4 slices ( today even 16 slices per rotation and 32 slices per

1 second) per rotation; in other words, multislice CT covers a volume up

to 8 times greater than spiral CT

– Enhanced z-axis spatial resolution: the speed of multislice scanning lows one to cover large volumes with thin slices With the aid ofrecostruction algorithms we can obtain a preserved slice profile and anoise reduction of 40%

al-– Isotropic voxels: the possibility of acquiring very thin slices allows one

to obtain voxels of the same size in the three spatial axes, with theappropiate recontruction FOV settings

This advantage, combined with the possibility of back reformatting thinslices, affords high-quality 3D and multiplanar reconstructions, with excellentanatomical detail (Fig 1 - 2)

This is particularly useful in high-resolution applications, such as CTangiography of the circle of Willis pouch, in the study of pulmonary embolism,and CT angiography of the lower limbs, in musculo-skeletal applications(hand, hip, ankle), in the study of the ear and the facial bones

10 Endoscopic surgery of the potential anatomical

E SQUILLACI ET AL. 11

A

Figure1 Volume Rendering CT image of normal abdominal aorta (A).

Abdominal aortic aneurysm MIP (B) and Volume Rendering CT (C) images.

MAGNETIC RESONANCE IMAGING

The evolution of MRI to its present status has been gradual A key milestoneoccurred when Lauterbur (1973) first revealed the imaging potential of MRI.The physics of MRI is more complex than CT, even though the principles ofpicture elements (pixels) derived from volume elements (voxels) within thebody are similar, along with the partial volume artefacts that can occur Much

of the competing and viewing software is similar; indeed many makes allowviewing of CT and MRI image on the same viewing console [2, 4]

The biggest and the more important component of an MRI system is themagnet

The magnet of an MRI system is rated using a unit of measure known as aTesla Another unit of measure commonly used with magnets is the Gauss (1T

Tesla = 10,000 Gauss) The magnets in use today in MRI are in the 0.5 T to 2.0T

T range

The fact that the MRI system does not use ionising radiation is a comfort tomany patients, as is the fact that MRI contrast materials have a very low inci-dence of side effects

Another major advantage of MRI is its ability to image in any plane

12 Endoscopic surgery of the potential anatomical

Figure 2

Volume Rendering CT of the abdominal splanchnic and iliac arteries.

An MRI system can create axial images as well as images in the sagittal andcoronal plane, or any degree in between, without the patient ever moving(fig.3).

MRI is still in its infancy MRI technology has been in widespread use forless than 20 years, compared with over 100 years for x-rays

Recent technical advances in hardware and software have allowed theacquisition of MR images that are largely free of artifacts secondary to bowelperistalsis or respiratory motion; images providing excellent anatomical detailcan now be obtained routinely Fast sequences have reduced image acquisitiontime, thereby improving patient acceptance and allowing more efficient utiliza-tion of machine time New three-dimensional sequences allow rapid image

acquisition, reducing section misregistration and motion artifacts whileimproving multiplanar reformation [5].

THE NECK

The neck contains important communications between the head and thebody, including air and food passages, major vessels and nerves and the spinalcord [4]

Its skeleton is primarily composed of the vertebral column Anteriorly, thehyoid bone and laryngeal and tracheal cartilages support the aerodigestivespaces These are suspended from the mandible and base of the skull by a sys-tem of muscles and ligaments

Anteriorly, strap muscles connect the respiratory skeleton and sternum.There are also muscular attachments from the hyoid to the tongue, mandible,and styloid The digastric muscle passes forward from the mastoid, attaches tothe hyoid, then ascends to the anterior mandible (Fig 4-5-6-7)

14 Endoscopic surgery of the potential anatomical

Figure 4 CT axial cervical section of neck region Caudal level 1 - Trachea; 2 - Left lateral

lobe of the thyroid gland; 3 - Carotid Artery; 4 - Jugular vein; 5 - Vertebral vein and artery; 6 -Sternocleidomastoid; 7 - Vertebral body; 8 - Rib

E SQUILLACI ET AL. 15

Figure 6 CT thin section through the lamina of the thyroid cartilage.

1 - Sternohyoid muscle; 2 - Lamina of the thyroid cartilage; 3 - Laringopharirynx;

4 - Sternocleidomastoid.

Figure 5 CT axial cervical section of neck region Cranial level.

1 - Sternohyoid muscle; 2 - Left and right lobes of the the thyroid;

3 - Carotial arteries.

The sternocleidomastoideus (SCM) divides the neck into anterior and posteriortriangles (scheme 1) The posterior triangle is largely muscular The anterior trian-gle, which contains most of the vital structures, can be divided into smaller trian-gles by muscles The anterior and posterior bellies of the digastric form thesubmandibular triangle The submental triangle is in the midline, between the ante-rior bellies The vascular or carotid triangle is inferior to the digastric and hyoid.The omohyoid is a small muscle, running at roughly 90 degrees to the SCM,from the hyoid to the scapula (Fig 8 - 9).

16 Endoscopic surgery of the potential anatomical

Figure 7 CT section through the mandible.

1 - Submandibular gland; 2 - Tongue; 3 - Oropharynx

Scheme 1 Anatomical triangles of muscular neck

E SQUILLACI ET AL. 17

Figure 8 Axial section through the mouth at the level of the upper alveolus.

1 - Masseteres, 2 - Ramus of mandible; 3 - Parotid glande; 4 - Medial pterygoid;

5 - Trapezius; 6 - Nasopharinx

Figure 9

Sagittal MRI of the neck:

1 - Body of hyoid bone

THE MEDIASTINUM (INTERPLEURAL SPACE)

The mediastinum lies near the median sagittal plane of the chest betweenthe right and left pleuræ It extends from the sternum in front to the vertebralcolumn behind, and contains all the thoracic viscera except the lungs It may bedivided for the purposes of description into two parts: an upper portion, abovethe upper level of the pericardium, which is named the superior mediastinum;and a lower portion, below the upper level of the pericardium This lower por-tion is again subdivided into three parts: the anterior mediastinum, in front ofthe pericardium; the middle mediastinum, containing the pericardium and itscontents; and the posterior mediastinum, behind the pericardium [6] (fig 10-11-12-13)

The Anterior Mediastinum - anterior wall is formed by the left transversusthoracis and the fifth, sixth, and seventh left costal cartilages It contains a quan-tity of loose areolar tissue, some lymphatic vessels, which ascend from the con-vex surface of the liver, two or three anterior mediastinal lymph glands, and thesmall mediastinal branches of the internal mammary artery

The Middle Mediastinum - is the broadest part of the interpleural space Itcontains the heart enclosed in the pericardium, the ascending aorta, the lowerhalf of the superior vena cava with the azygos vein opening into it, the bifurcation

18 Endoscopic surgery of the potential anatomical

Figure 10 Axial CT section of the mediastinum:

1 - Trachea; 2 - Right brachiocephalic vein; 3 - Brachiocephalic artery; 4 - Left rotid artery; 5 - Left subclavian artery; 6 - Oesophagus; 7 - Left brachiocephalic vein; 8 - Manubrium of sterni

ca-E SQUILLACI ET AL. 19

Figure 11 Axial CT section of the mediastinum

1 - Trachea; 2 - Right brachiocephalic vein; 3 - Left brachiocephalic vein;

4 - Brachiocephalic artery; 5 - Aortic arch; 6 - Oesophagus

Figure 12 Axial CT section of the mediastinum

1 - Trachea bifurcation; 2 - Superior vena cava; 3 - Ascending Aorta;

4 - Descending Aorta; 5 - Pulmonary Artery; 6 - Fat

of the trachea and the two bronchi, the pulmonary artery dividing into its twobranches, the right and left pulmonary veins, the phrenic nerves and somebronchial lymph glands (Fig 14A - B - C).

20 Endoscopic surgery of the potential anatomical

Figure 13 Axial CT section of the mediastinum

1 - Right Auricola; 2 - Ascending Aorta; 3 - Right Ventricle; 4 - Left Atrium;

5 - Descending Aorta

A

The Posterior Mediastinum - is an irregular triangular space runningparallel with the vertebral column; it is bounded in front by the pericardiumabove, and by the posterior surface of the diaphragm below, behind by the ver-tebral column from the lower border of the fourth to the twelfth thoracic verte-

B

C

Figure 14 MR Angiography with MIP algorithm of normal vascular anatomy of thoracic

ves-sels (A) Sagittal CT MPR (B) and Volume Rendering (C).

bra, and on either side by the mediastinal pleura It contains the thoracic part ofthe descending aorta, the azygos and the two hemiazygos veins, the vagus andsplanchnic nerves, the esophagus, the thoracic duct and some lymph glands.

THE PLEURA

The pleura is a delicate serous membrane arranged in the form of a closedinvaginated sac that invests each lung (Fig 15-16) The pulmonary pleura cov-ers the surface of the lung and dips into the fissures between its lobes The pari-etal pleura is the rest of the membrane and lines the inner surface of the chestwall, covers the diaphragm and is reflected over the structures occupying themiddle of the thorax

The two layers are continuous with one another around and below the root

of the lung; in health they are in actual contact with one another, but the tial space between them is known as the pleural cavity When the lung col-lapses or when air or fluid collects between the two layers, the cavity becomesapparent The right and left pleural sacs are entirely separate from themediastinum

poten-Reflections of the pleura start at the sternum, the pleura passes laterally and

is reflected upon the sides of the bodies of the vertebræ

From the vertebral column the pleura passes to the side of the pericardium;

it then covers the back part of the root of the lung, from the lower border ofwhich a triangular sheet descends vertically toward the diaphragm This sheet

is the posterior layer of a wide fold, known as the pulmonary ligament Fromthe back of the lung root, the pleura may be traced over the costal surface of the

22 Endoscopic surgery of the potential anatomical

Figure 15

Volume Rendering coronal CT image of the thorax Visceral pleura is well evident (arrows).

lung, the apex and base and also over the sides of the fissures between thelobes, on to its mediastinal surface and the front part of its root [4].

THE ABDOMEN

The abdomen is the largest cavity of the body It has an oval shape, the tremities of the oval being directed upward and downward The upper extrem-ity is formed by the diaphragm, which extends like a dome over the abdomen,

ex-so that the cavity extends high into the bony thorax, reaching on the right side,

in the mammary line, to the upper border of the fifth rib; on the left side it fallsbelow this level by about 2.5 cm The lower extremity is formed by the struc-tures which clothe the inner surface of the bony pelvis, principally the Levatorani and coccygeus on either side (Fig 17-18) [6]

The cavity is wider above than below, and measures more in the verticalthan in the transverse axis

It is artificially divided into two parts: an upper and larger part, the abdomenproper; and a lower and smaller part, the pelvis These two cavities are notseparated from each other but the border between them is marked by the supe-rior aperture of the lesser pelvis

The abdomen contains the greater part of the digestive tube; the liver, thepancreas, the spleen, the kidneys and the suprarenal glands (Fig 19-20) Most

Figure 16 CT axial plane The two pleural layers are visible in a case of effusion (arrows).

24 Endoscopic surgery of the potential anatomical

Figure 17 Axial Volume Rendering CT of abdomen.

1 - Colon; 2 - Liver; 3 - Kidneys; 4 - Spleen; 5 - Fat

Figure 18 Multislice CT Internal organs, as well as muscles and skin, are clearly visible on

3D CT abdominal reconstruction.

E SQUILLACI ET AL. 25

Figure 19 MR coronal imaging of the superior abdomen Anterior plane.

1 - Portal vein; 2 - Left branch of portal vein; 3 - Right branch of portal vein;

4 - Liver; 5 - Stomach

Figure 20 MR coronal image of the superior abdomen Posterior plane.

1 - Liver; 2- Kidneys; 3 - Spleen; 4 - Perirenal Fat;

of these structures, as well as the wall of the cavity in which they are contained,are more or less covered by an extensive and complicated serous membrane,the peritoneum.

THE PERITONEUM (TUNICA SEROSA)

The peritoneum is the largest serous membrane in the body and consists, inthe male, of a closed sac, a part of which is applied against the abdominalparietes, while the remainder is reflected over the contained viscera In the fe-male, the peritoneum is not a closed sac, since the free ends of the uterine tubesopen directly into the peritoneal cavity The part which lines the parietes isnamed the parietal portion of the peritoneum; that which is reflected over thecontained viscera constitutes the visceral portion of the peritoneum The freesurface of the membrane is smooth, covered by a layer of flattenedmesothelium and lubricated by a small quantity of serous fluid Hence the vis-cera can glide freely against the wall of the cavity or against one another withthe least possible amount of friction The attached surface is rough, being con-nected to the viscera and inner surface of the parietes by means of areolar tis-sue, termed the subserous areolar tissue The parietal portion is loosely con-nected with the fascial lining of the abdomen and pelvis, but is more closelyadherent to the under surface of the diaphragm and also in the middle line ofthe abdomen The space between the parietal and visceral layers of the perito-neum is named the peritoneal cavity; but under normal conditions this cavity ismerely a potential one, since the parietal and visceral layers are in contact Theperitoneal cavity gives off a large diverticulum, the omental bursa, which is sit-uated behind the stomach and adjoining structures; the neck of communicationbetween the cavity and the bursa is termed the epiploic foramen (foramen ofWinslow) Formerly the main portion of the cavity was described as the greater,W

and the omental bursa as the lesser sac [7, 8]

Vertical Disposition of the Main Peritoneal Cavity (greater sac)

It is convenient to trace this from the back of the abdominal wall at the level

of the umbilicus On following the peritoneum upward from this level it is seen

to be reflected around a fibrous cord, the ligamentum teres (obliterated cal vein),which reaches from the umbilicus to the under surface of the liver.This reflection forms a somewhat triangular fold, the falciform ligament of theliver, attaching the upper and anterior surfaces of the liver to the diaphragm andabdominal wall With the exception of the line of attachment of this ligament,

umbili-26 Endoscopic surgery of the potential anatomical

the peritoneum covers the whole of the under surface of the anterior part of thediaphragm and continues on from it to the upper surface of the right lobe of theliver as the superior layer of the coronary ligament and on to the uppersurface of the left lobe as the superior layer of the left triangular ligament ofthe liver Covering the upper and anterior surfaces of the liver, it is continuedaround its sharp margin on to the under surface, where it presents the follow-ing relations:

(a) It covers the under surface of the right lobe and is reflected from the back

part of this on to the right suprarenal gland and upper extremity of the right ney, forming in this situation the inferior layer of the coronary ligament; a spe-cial fold, the hepatorenal ligament, is frequently present between the inferiorsurface of the liver and the front of the kidney From the kidney it is carrieddownward to the duodenum and right colic flexure and medialward in front ofthe inferior vena cava, where it is continuous with the posterior wall of theomental bursa Between the two layers of the coronary ligament there is a largetriangular surface of the liver devoid of peritoneal covering; this is named thebare area of the liver, and is attached to the diaphragm by areolar tissue To-ward the right margin of the liver the two layers of the coronary ligament grad-ually approach each other and ultimately fuse, to form a small, triangular foldconnecting the right lobe of the liver to the diaphragm and named the right tri-angular ligament of the liver The apex of the triangular bare area correspondswith the point of meeting of the two layers of the coronary ligament, its basewith the fossa for the inferior vena cava

kid-(b) It covers the lower surface of the quadrate lobe, the under and lateral

sur-faces of the gall-bladder and the under surface and posterior border of the leftlobe; it is then reflected from the upper surface of the left lobe to the diaphragm

as the inferior layer of the left triangular ligament and from the porta of theliver and the fossa for the ductus venosus to the lesser cuvature of the stomachand the first 2.5 cm of the duodenum as the anterior layer of the hepatogastricand hepatoduodenal ligaments, which together constitute the lesser omentum

If this layer of the lesser omentum be followed to the right, it will be found toturn around the hepatic artery, bile duct and portal vein and become continuouswith the anterior wall of the omental bursa, forming a free folded edge of theperitoneum Traced downward, it covers the antero-superior surface of thestomach and the commencement of the duodenum and is carried down into alarge free fold, known as the gastrocolic ligament or greater omentum.Reaching the free margin of this fold, it is reflected upward to cover the underand posterior surfaces of the transverse colon and thence to the posterior ab-dominal wall as the inferior layer of the transverse mesocolon It reaches theabdominal wall at the head and anterior border of the pancreas, is then carrieddown over the lower part of the head and over the inferior surface of the pan-creas on the superior mesenteric vessels and thence to the small intestine as the

anterior layer of the mesentery It encircles the intestine, and subsequently may

be traced as the posterior layer of the mesentery, upward and backward to theabdominal wall From this it sweeps down over the aorta into the pelvis, where

it invests the sigmoid colon, its reduplication forming the sigmoid mesocolon.Leaving first the sides and then the front of the rectum, it is reflected on to theseminal vesicles and fundus of the urinary bladder and, after covering the up-per surface of that viscus, is carried along the medial and lateral umbilical liga-ments on to the back of the abdominal wall to the level from which a start wasmade

THE RETROPERITONEUM

The retroperitoneum is an anatomical compartment contained between theposterior parietal peritoneum and the trasversalis fascia It is limited, from be-low upward, by the under surface of diaphragm and, downward, is separatedfrom the pelvis by iliac vessels (Fig 21-22-23-24) [6, 7]

Laterally, the retroperitoneum is limited by the muscles of abdominal wall.The model divides the retroperitoneum into three distinct compartments:posterior pararenal space, perirenal space and anterior pararenal space.The posterior pararenal space contains only fat and is rarely the site of fluidcollection

28 Endoscopic surgery of the potential anatomical

Figure 21 Axial CT This section passes throught the body of the first lumbar vertebra The

kidneys are embedded in the perirenal fat At the lateral border of the kidney, the two layers of the renal fascia are fused D: duodenum; P: pancreas.

E SQUILLACI ET AL. 29

Figure 22 CT Coronal plane.

Retroperitoneal kidneys (inside a litiasic image: point of arrow), liver and spleen Psoas muscles are visible on the left and on the right of the spine (P)

Figure 23 CT axial plane throught the XI thoracic vertebra The adrenals (SRG) have a

costant relationship with the diaphragmatic crura.

The right crus of the diaphragm (arrow) is often bulky.

The pancreas is clearly visible in the more anterior planes.

The two perirenal spaces contain the kidneys, renal pelvis and proximalureters, adrenal glands, and perirenal fat (Fig 25-26) [9, 10].

30 Endoscopic surgery of the potential anatomical

Figure 24 CT Volume Rendering The Abdominal Aorta is visible until iliac bifurcation.

Figure 25 CT Volume Rendering The kidneys and the urinary tract; on the left is visible the

double district.

The anterior pararenal space contains the retroperitoneal segments of thecolon and duodenum, the pancreas and the root of the small intestinalmesentery (Fig 27-28).

Figure 26

Perirenal spaces Posterior and ante- rior renal fascia (ARF, PRF) (point

of arrows).

1 - Posterior pararenal space;

2 - Perirenal space;

3 - Anterior pararenal space

Figure 27

Axial plane throught the retroperitoneal structures.

1 - Kidneys;

2 - Head of the pancreas;

3 - Bowel loop;

4 - Cyst of right kidney